Dong Liang, Kumar Hemant, Anasori Babak, Gogotsi Yury, Shenoy Vivek B
Department of Materials Science and Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
Department of Materials Science & Engineering and A.J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.
J Phys Chem Lett. 2017 Jan 19;8(2):422-428. doi: 10.1021/acs.jpclett.6b02751. Epub 2017 Jan 5.
Two-dimensional (2D) materials that display robust ferromagnetism have been pursued intensively for nanoscale spintronic applications, but suitable candidates have not been identified. Here we present theoretical predictions on the design of ordered double-transition-metal MXene structures to achieve such a goal. On the basis of the analysis of electron filling in transition-metal cations and first-principles simulations, we demonstrate robust ferromagnetism in TiMnCT monolayers regardless of the surface terminations (T = O, OH, and F), as well as in HfMnCO and HfVCO monolayers. The high magnetic moments (3-4 μB/unit cell) and high Curie temperatures (495-1133 K) of these MXenes are superior to those of existing 2D ferromagnetic materials. Furthermore, semimetal-to-semiconductor and ferromagnetic-to-antiferromagnetic phase transitions are predicted to occur in these materials in the presence of small or moderate tensile in-plane strains (0-3%), which can be externally applied mechanically or internally induced by the choice of transition metals.
具有强铁磁性的二维（2D）材料一直是纳米级自旋电子学应用的研究热点，但尚未找到合适的候选材料。在此，我们提出了关于有序双过渡金属MXene结构设计的理论预测，以实现这一目标。基于对过渡金属阳离子中电子填充情况的分析和第一性原理模拟，我们证明了TiMnCT单层无论表面端基（T = O、OH和F）如何，以及HfMnCO和HfVCO单层中都具有强铁磁性。这些MXene的高磁矩（3 - 4 μB/晶胞）和高居里温度（495 - 1133 K）优于现有的二维铁磁材料。此外，预计在这些材料中，当存在小或中等程度的面内拉伸应变（0 - 3%）时，会发生半金属到半导体以及铁磁到反铁磁的相变，这种应变可以通过外部机械施加或通过选择过渡金属内部诱导产生。
